bumping with one of the beta threads and another thread about this in questing
https://us.forums.blizzard.com/en/wow/t/sinfall-transport-network-l3-oribos-portal-is-missing/696488
https://us.forums.blizzard.com/en/wow/t/venthyr-level-3-mirror-network-oribos-portal/805071
They forreal probably forgot to implement it because it wasn’t implemented in beta